Levamisole-adulterated cocaine: an excellent review

March 31, 2012, 3:00 pm


Levamisole in cocaine: Unexpected news from an old acquaintance. Larocque A, Hoffman RS. Clin Toxicol 2012 Apr;50:231-241.


Since 2003, batches of cocaine seized by U.S. drug authorities have contained the drug levamisole. By 2009, almost 70%  of confiscated cocaine shipments were adulterated with this drug.

Levamisole in the past had been used in humans to treat both rheumatologic conditions and cancer. However, when it became clear that levamisole was associated with significant adverse effects, its approval was withdrawn. It still has use in veterinary medicine as an anti-helminthic agent.

This comprehensive review article — 131 references — is worth reading for toxicologists and those with special interests in cocaine and its adulterants.   It did get somewhat tedious when discussing the serology of levamisole exposure, reminding me why I decided against pursuing a career in Internal Medicine:

The c-ANCA occurs almost exclusively a a result of antibodies against proteinase 3 (PR3). In contrast, p-ANCA antibodies target different neutrophil granule constituents such as MPO, human neutrophil elastase (HNE) and sometimes PR3. Clinical differentiation from CIMDL and WG can be difficult and serologic testing is characterized by ANCA presence in both conditions. However, specific testing for ANCA reacing with HNE seems to allow this differentiation. WG typically displays a pattern of c-ANCA directed againt PRE, and MPA typically displays a pattern of p-ANCA targeting MPO. In CIMDL, the most typicaly pattern is of p-ANCA with negative MPO and sometimes positive PR3.

By this time it seemed like I was in acronym hell, and I was mumbling OMG and WTF!

However, there are a number points in this article that all emergency physicians and toxicologists should be aware of:

  • Hematological complications of levamisole include neutroopenia and thrombocytopenia.
  • Dermatological complications of levamisole include cutaneous vasculitis, often causing facial and ear lobe necrosis.
  • Neutropenia, thrombocytopenia, and vasculitis usualy resolve when the drug is discontinued.
  • Unusual known complications of levamisole, such as leukoencephalopathy and SIADH are rarely seen in patients exposed through adulterated cocaine.

Levamisole has a number of pharmacological actions that might explain why it is frequently added to cocaine. Evidence suggests that it inhibits norepinephrine re-uptake, inhibits monoamine oxidase, acts as an agonist at nicotinic receptors, and undergoes metabolism into an amphetamine-like intermediate. It may also increase concentration of endogenous opiate compounds and increase dopamine.

The authors stress the importance of identifying levamisole-induced skin and blood complications. Doing so will not only avoid instituting unnecessary diagnostic work-ups and potentially harmful therapy, but also allow the patient to be counseled about the good prognosis expected if further exposure to levamisole is avoided.

Related posts:

Cocaine, levamisole, and the white blood count 

Dramatic pictures: vasculitis caused by levamisole-contaminated cocaine

Scrotal gangrene after smoking crack

Unusual complication of cocaine abuse

Case reports: neutropenia associated with levamisole-adulterated cocaine

Why is the antihelminthic drug levamisole used to adulterate cocaine?

Cocaine adulterated with levamisole implicated in 21 cases of agranulocytosis

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